Dietary Supplements: Sometimes a Placebo Is Better

Dietary supplements live in a unique regulatory space. That space lies somewhere between food and drugs. Sometimes that’s just fine. Vitamins and minerals that your body really needs can be well-regulated for purity and safety. But therapeutic agents also squeeze into this space. For example, glucosamine and chondroitin supplements advertise benefits like “joint mobility.” People with osteoarthritis take them expecting they will help their symptoms. But they won’t.

In fact, in a new study published in Arthritis & Rheumatology, an intent-to-treat analysis showed that glucosamine and chondroitin was inferior to placebo for reduction of joint pain.

Intent-to-treat is a rigorous testing method that counts the results of all patients in a clinical trial, even if they stop taking the drug. In this trial, more people stopped taking the real drug than the placebo due to side effects. Take those people out of the analysis and the glucosamine/chondroitin product was no better and no worse than a placebo.

But dietary supplements can make slippery claims without proving they are true. “Data on file” is all their manufacturers need. These products pretend to offer a benefit for which they need no definitive proof.

You’ve seen or heard the ads. They talk about “help with joint flare-ups” and “supporting joint mobility.” For people concerned about obesity, they make fantastic claims about weight loss that don’t hold up under scrutiny. And then, the fine print or fast-talking disclaimer follows. “These claims have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.”

In other words, you should not believe a single word of those ads.

Click here for more from the New York Times, here for the study in Arthritis & Rheumatology, here for more on glucosamine and chondroitin, and here for more on dietary supplements and alternative medicine.

Bones, photograph © Alice / flickr

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January 31, 2017